As you probably can tell, there's not much in Cranberry,
Butler City Hunting and Fishing Club
P.O. Box 105
Butler, Pa. 16003
Outdoor- Pistol, rifle, archery, trap
Private CLub
Give them a shout. Since you're only here for the summer, they may let you do a limited membership.
http://www.bchfclub.org/
Check out the PA State Game land:
Allegheny SGL #203 Access RT 228
Anthony Arms has an indoor range:
http://www.anthonyarms.com/range/
It's about an hour away from Cranberry Township
http://suite101.com/article/indoor-shooting-ranges-in-pittsburgh-a344390
It's a start. As you can see, there really is not much up there.
If you haven't been to forum.pafoa.org- give them a shout, as well. It's the Pennsylvania Firearms Owners Association forum and someone from your area may have a membership to a local club that could help you with some range time.
HTH
D